Cosmology With A Dark Refraction Index

We review Gordon's optical metric and the transport equations for the amplitude and polarization of a geometrical optics wave traveling in a gravity field. We apply the theory to the FLRW cosmologies by associating a refraction index with the cosmic fluid. We then derive an expression for the accumulated effect of a refraction index on the distance redshift relations and fit the Hubble curve of current supernova observations with a non-accelerating cosmological model. We also show that some observational effects caused by inhomogeneities, e.g. the Sachs-Wolfe effect, can be interpreted as being caused by an effective index of refraction, and hence this theory could extend to other speed of light communications such as gravitational radiation and neutrino fluxes.Comment: 21 pages, 3 figure

The Impact of Personality Type on Undergraduate College Student Success at Oklahoma State University

The purpose of this descriptive/causal-comparative study was to determine if relationships existed between individual personality types as determined by the Do What You Are (DWYA) on-line personality inventory and gender, ethnicity, area of academic study, entering and exiting grade point averages (GPA), and time to degree completion of undergraduate students at the case study institution. Data were collected over a six year period by the institution\u27s career development center. The student respondents were undergraduates and were self-selected to take the inventory. The sample included 2, 533 undergraduate students surveyed between 2003 and 2007. Statistical analysis utilized scores on the four continuous dimension scales on the personality inventory and other student demographic variables. Student scores on the DWYA served as the chief independent or predictor variable for all of the outcome variables. The first and second research questions examined the descriptive information of the majority types in each of the academic areas. The third and fourth questions examined the relationship between personality type and undergraduate grade point averages of the respondents. The fifth question examined the relationship between personality type and the student\u27s academic status (continuing, dropped, or graduated). The sixth question sought to find a correlation between personality type and the time to degree obtainment. The four-way factorial ANOVA found one significant main effect interaction between the judging / perceiving dimension scale where judging types had a significantly higher mean GPA than perceiving types. ANOVA also discovered a significant two-way interaction between mean GPA\u27s of the respondents and the extroversion/introversion scale and the thinking/feeling scale. Introverted thinkers had a higher mean GPA than extroverted thinkers. The Chi square statistic was found to be significant for feeling perceiving (FP) personality types (ENFP, ESFP, INFP, ISFP) and the dropout status

Distance-redshift from an optical metric that includes absorption

We show that it is possible to equate the intensity reduction of a light wave caused by weak absorption with a geometrical reduction in intensity caused by a "transverse" conformal transformation of the spacetime metric in which the wave travels. We are consequently able to modify Gordon's optical metric to account for electromagnetic properties of ponderable material whose properties include both refraction and absorption. Unlike refraction alone however, including absorption requires a modification of the optical metric that depends on the eikonal of the wave itself. We derive the distance-redshift relation from the modified optical metric for Friedman-Lema\^itre-Robertson-Walker spacetimes whose cosmic fluid has associated refraction and absorption coefficients. We then fit the current supernovae data and provide an alternate explanation (other than dark energy) of the apparent acceleration of the universe.Comment: 2 figure

Electrovac pppp-waves

New exact solutions of the Einstein-Maxwell field equations that describe $pp$-waves are presented

The Theory of Caustics and Wavefront Singularities with Physical Applications

This is intended as an introduction to and review of the work of V, Arnold and his collaborators on the theory of Lagrangian and Legendrian submanifolds and their associated maps. The theory is illustrated by applications to Hamilton-Jacobi theory and the eikonal equation, with an emphasis on null surfaces and wavefronts and their associated caustics and singularities.Comment: Figs. not include

General relativistic spinning fluids with a modified projection tensor

An energy-momentum tensor for general relativistic spinning fluids compatible with Tulczyjew-type supplementary condition is derived from the variation of a general Lagrangian with unspecified explicit form. This tensor is the sum of a term containing the Belinfante-Rosenfeld tensor and a modified perfect-fluid energy-momentum tensor in which the four-velocity is replaced by a unit four-vector in the direction of fluid momentum. The equations of motion are obtained and it is shown that they admit a Friedmann-Robertson-Walker space-time as a solution.Comment: Submitted to General Relativity and Gravitatio

A kinetic theory of diffusion in general relativity with cosmological scalar field

A new model to describe the dynamics of particles undergoing diffusion in general relativity is proposed. The evolution of the particle system is described by a Fokker-Planck equation without friction on the tangent bundle of spacetime. It is shown that the energy-momentum tensor for this matter model is not divergence-free, which makes it inconsistent to couple the Fokker-Planck equation to the Einstein equations. This problem can be solved by postulating the existence of additional matter fields in spacetime or by modifying the Einstein equations. The case of a cosmological scalar field term added to the left hand side of the Einstein equations is studied in some details. For the simplest cosmological model, namely the flat Robertson-Walker spacetime, it is shown that, depending on the initial value of the cosmological scalar field, which can be identified with the present observed value of the cosmological constant, either unlimited expansion or the formation of a singularity in finite time will occur in the future. Future collapse into a singularity also takes place for a suitable small but positive present value of the cosmological constant, in contrast to the standard diffusion-free scenario.Comment: 17 pages, no figures. The present version corrects an erroneous statement on the physical interpretation of the results made in the original publicatio